11.2 Supraglottic Airway (SGA) Devices & Tracheostomy Management

11.2 Supraglottic Airway (SGA) Devices & Tracheostomy Management

Clinical Indications, Contraindications & Role of SGAs in BLS Resuscitation

In prehospital resuscitation, rapid establishment of a reliable airway is critical to oxygenation, ventilation, and neurological survival. Under the Canadian Paramedic Competence Framework (CPCF Appendix A #21), supraglottic airway (SGA) devices represent the primary advanced airway modality within the Primary Care Paramedic (PCP) scope of practice. Historically, endotracheal intubation (ETI) was considered the gold standard; however, extensive prehospital evidence demonstrates that paramedic ETI is associated with prolonged chest compression interruptions, high rates of unrecognized esophageal intubation, and variable first-pass success. In contrast, SGAs provide a high first-pass insertion success rate (>90%), require minimal interruption of chest compressions (<5 seconds), and do not require laryngoscopic visualization of the vocal cords.

Clinical Indications

1. Out-of-Hospital Cardiac Arrest (OHCA): Primary advanced airway management during cardiopulmonary resuscitation in unresponsive adult and pediatric patients.
2. Failed Basic Airway / Rescue Ventilation: When bag-valve-mask (BVM) ventilation is ineffective or impossible ("cannot ventilate, cannot oxygenate") despite two-rescuer technique, positioning, and basic adjuncts (OPA/NPA).
3. Profoundly Unresponsive Patients Without Gag Reflex: Apneic or severely hypoventilating patients with absent protective airway reflexes requiring definitive positive pressure ventilation.

Contraindications & Limitations

• Absolute Contraindications:
  • Intact or semi-intact gag reflex.
  • Severe trismus, clenched jaw, or inability to open the mouth.
  • Known esophageal pathology (strictures, caustic burns, esophageal varices, Zenker diverticulum) for devices with esophageal cuffs (e.g., King LT).
  • Complete upper airway obstruction caused by an impacted foreign body.
• Relative Contraindications & Limitations: Massive facial trauma, distorted pharyngeal anatomy, extreme obesity, or high airway resistance/low lung compliance (e.g., severe bronchospasm or morbid obesity), where airway seal pressures may be exceeded, causing air leaks into the pharynx.

Prehospital SGA Modalities

• i-gel: A second-generation SGA constructed with an innovative, non-inflatable medical-grade thermoplastic elastomer (SEBS) cuff. The cuff softens at body temperature and molds accurately to the perilaryngeal architecture, creating an anatomical seal over the laryngeal inlet without pressure necrosis. It features an integrated bite block, a wide buccal stabilizer, and a dedicated gastric suction channel.
• King LT-D / King LTS-D: A disposable supraglottic tube with two inflatable cuffs inflated simultaneously via a single pilot balloon. The large proximal (oropharyngeal) cuff seals the nasopharynx and mouth, while the smaller distal (esophageal) cuff blocks the esophagus, isolating the glottis between the cuffs. The King LTS-D model incorporates a gastric drainage channel.
• Laryngeal Mask Airway (LMA): An elliptical silicone cuff designed to sit over the supraglottic opening, inflated with air to form an airtight seal against the laryngeal perimeter.

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Device Sizing, Insertion Technique & Gastric Decompression

SGA performance depends entirely on selecting the appropriate size and seating the cuff accurately within the hypopharynx.

Sizing Criteria

Unlike basic OPAs, which are sized anatomically by facial landmarks, supraglottic airways are sized according to patient body weight (i-gel) or patient height and weight (King LT).

Step-by-Step i-gel Insertion Protocol

1. Preparation & Pre-Oxygenation: Confirm cardiac arrest or deep unresponsiveness. Ensure continuous CPR and pre-oxygenation via BVM. Check that the packaging is intact and verify size based on estimated ideal body weight.
2. Lubrication: Remove the i-gel from its cradle. Apply a small bolus of water-soluble lubricant to the flat surface of the transfer plate. Coat the back and sides of the non-inflatable cuff smoothly. Never lubricate the front bowl/orifice, as lubricant can enter the airway.
3. Patient Positioning: Place the patient in the "sniffing" position (atlanto-occipital extension with slight cervical flexion). In suspected trauma, maintain neutral manual in-line stabilization (MILS).
4. Insertion: Grasp the i-gel firmly along the integrated bite block. With the opposite hand, gently pull the patient's chin downward to open the mouth. Introduce the lubricated cuff tip into the mouth, pressing against the hard palate. Glide the device smoothly downward along the posterior pharyngeal wall. Do not force; follow the anatomical curvature.
5. Seating: Advance the device until definitive resistance is felt. At this point, the distal tip rests in the upper esophagus, and the cuff bowl snugly caps the larynx. The patient's incisors should align with the black horizontal marker on the bite block.
6. Securing: Secure the i-gel using the included manufacturer strap or a commercial advanced airway tube holder. Never use adhesive tape alone, as it easily detaches when wet with saliva.

Gastric Decompression Channel Utilization

Second-generation SGAs (i-gel and King LTS-D) possess an integrated gastric channel running parallel to the ventilation conduit. During positive pressure ventilation, gastric insufflation frequently occurs. Paramedics must insert a well-lubricated 10 to 14 French gastric tube through this channel into the stomach, apply gentle suction, and vent air and liquid emesis. Decompressing the stomach dramatically lowers intragastric pressure, prevents regurgitation around the cuff, and decreases diaphragmatic splinting, thereby improving lung compliance.

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Airway Confirmation & Waveform Capnography Standards

Insertion of an advanced airway requires instantaneous and continuous dual-confirmation to eliminate the risk of unrecognized esophageal misplacement or laryngeal displacement.

Airway Confirmation Dual Standard:
[1. Primary Clinical Confirmation]   ➔ 5-Point Auscultation + Chest Rise + Absence of Gastric Sounds
[2. Objective Quantitative Standard] ➔ Continuous Waveform Capnography (Rectangular Plateau EtCO2)

1. Primary Clinical Confirmation

Immediately deliver gentle positive pressure breaths and assess:

• Bilateral Symmetrical Chest Rise: Confirm visible chest expansion during inspiration.
• 5-Point Auscultation: Using a stethoscope, auscultate:
  1. Left mid-axillary line
  2. Right mid-axillary line
  3. Left anterior mid-clavicular chest
  4. Right anterior mid-clavicular chest
  5. Epigastrium (must be completely silent; gurgling indicates esophageal positioning or massive cuff leak).
• Absence of Pharyngeal Air Leak: Listen for loud hissing around the mouth during bag compression.

2. Continuous Quantitative Waveform Capnography (The Gold Standard)

Clinical auscultation alone is notoriously unreliable in noisy prehospital environments. Continuous waveform capnography is the mandatory, objective standard of care for confirming and monitoring any advanced airway:

• Waveform Morphology: Must display a crisp, rectangular square-wave pattern across all 4 phases (Phase I: inspiratory baseline; Phase II: rapid expiratory upstroke; Phase III: alveolar plateau; Phase 0: rapid inspiratory downstroke).
• End-Tidal CO2 Values (PetCO2): In cardiac arrest, initial PetCO2 reflects cardiac output produced by chest compressions. High-quality CPR generates a PetCO2 of 15 to 25 mmHg. An abrupt, sustained spike in PetCO2 (e.g., rising rapidly to 35 to 45 mmHg) is the earliest physiological indicator of Return of Spontaneous Circulation (ROSC), occurring prior to a palpable pulse.
• Unrecognized Misplacement: A flatline capnogram (EtCO2 = 0) with absent square waves indicates that the device is in the esophagus, completely displaced, or that there is zero pulmonary blood flow. The device must be immediately re-evaluated or removed.

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Troubleshooting Airway Emergencies: The DOPE Mnemonic

When a previously stable patient with an advanced airway experiences sudden deterioration—manifested by increased resistance to BVM compression, dropping SpO2, vanishing chest rise, or a collapsing capnography waveform—the paramedic must immediately work through the standardized DOPE mnemonic:

+-----------------------------------------------------------------------------------------+
|                                 THE DOPE TROUBLESHOOTING MNEMONIC                       |
+---+-----------------+---------------------------------+---------------------------------+
| D | Dislodgement    | Cuff displaced into pharynx;   | Check depth marker at incisors; |
|   |                 | tube dislodged into esophagus   | re-seat or remove and BVM       |
+---+-----------------+---------------------------------+---------------------------------+
| O | Obstruction     | Mucus plug, blood clot, biting, | Inspect tube; suction lumen;    |
|   |                 | kinking, cuff herniation        | insert bite block; unkink       |
+---+-----------------+---------------------------------+---------------------------------+
| P | Pneumothorax    | Tension pneumothorax from PPV,  | Auscultate breath sounds; check |
|   |                 | barotrauma, or chest trauma     | for tracheal shift; request ACP |
+---+-----------------+---------------------------------+---------------------------------+
| E | Equipment       | Disconnected O2 line, dead BVM  | Disconnect circuit; ventilate   |
|   | Failure         | valve, monitor sensor failure   | directly with fresh BVM & tank  |
+---+-----------------+---------------------------------+---------------------------------+

1. D - Dislodgement: The SGA has slipped backward out of the hypopharynx or rotated sideways. Action: Check depth markers. If dislodged, push the device gently back into the hypopharynx until resistance is felt; if ventilations cannot be re-established, pull the device and return to two-rescuer BVM.
2. O - Obstruction: Secretions or blood clogging the lumen, the patient biting the tube as consciousness returns, or the cuff folding over the glottis. Action: Pass a flexible suction catheter through the lumen; ensure a bite block is present; unkink the circuit.
3. P - Pneumothorax: Positive pressure ventilation can rupture an alveolar bleb or convert a simple pneumothorax into a life-threatening tension pneumothorax. Signs: Severe resistance to bagging, absent breath sounds unilaterally, hyperresonance, jugular venous distension, tracheal deviation, and hemodynamic collapse. Action: Immediate needle chest decompression (by ACP or trained PCP where provincial scope permits).
4. E - Equipment Failure: The oxygen supply is exhausted, tubing is pinched, the BVM duckbill valve is stuck, or the capnograph adapter is clogged with vomitus. Action: Disconnect the BVM from the advanced airway, squeeze the bag into your hand to test valve mechanics, verify tank pressure, and switch to a backup manual resuscitator.

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Emergency Management of Mature Tracheostomies and Laryngectomies

Paramedics frequently encounter patients with artificial stomas in community paramedicine and acute emergency response. Misunderstanding the underlying anatomy can lead to fatal asphyxia.

Anatomical Distinction: Tracheostomy vs Total Laryngectomy

• Tracheostomy: A surgical opening made through the anterior neck into the cervical trachea (usually between the second and third tracheal rings). The patient's upper airway anatomy remains intact; the larynx is preserved. Air can theoretically move through both the mouth/nose and the stoma. If the tracheostomy tube becomes obstructed, the patient may still be ventilated through the upper airway if the stoma is occluded.
• Total Laryngectomy: Performed for advanced laryngeal cancer. The larynx and vocal cords are completely excised. The distal trachea is bent forward and sutured directly flush to the anterior neck skin, creating a permanent terminal stoma. The patient is a total neck breather. There is zero connection between the mouth/pharynx and the lungs. Ventilating via the mouth or nose is physiologically impossible.

Clinical Presentation of Tracheostomy Emergencies

Patients typically present in severe respiratory distress, cyanosis, and agitation secondary to mucus plugging (inspissated, dehydrated tracheobronchial secretions blocking the cannula), bleeding, or cannula displacement into the pretracheal soft tissues ("false tract").

Step-by-Step Resuscitation Protocol for Tracheostomy Distress

1. Assess Patency & Administer Oxygen: Apply high-flow oxygen via a dedicated tracheostomy collar or hold a non-rebreather mask directly over the neck stoma. Check for air movement.
2. Remove and Inspect Inner Cannula: Modern tracheostomy appliances utilize a dual-cannula system. The inner cannula unlocks with a quarter-turn. Immediately withdraw the inner cannula; if it is occluded with a thick mucus plug, ventilations may instantly improve. Clean the cannula with sterile saline or replace it with a spare clean cannula from the patient's home kit.
3. Sterile Flexible Catheter Suctioning: If respiratory distress persists after removing the inner cannula:
   • Use aseptic technique: don sterile gloves.
   • Pre-oxygenate the patient.
   • Select a flexible suction catheter whose outer diameter does not exceed half the internal diameter of the tracheostomy tube.
   • Gently insert the catheter into the tracheostomy tube without suction until mild resistance is felt or the patient coughs (typically 8 to 12 cm, representing tube length plus 1 to 2 cm).
   • Apply suction at -80 to -120 mmHg only while withdrawing the catheter in a rotational motion for no more than 10 seconds.
   • Re-oxygenate and reassess.
4. Assisted Positive Pressure Ventilation:
   • A standard manual resuscitation bag (BVM) connects directly to the universal 15 mm connector on the tracheostomy tube hub.
   • Squeeze gently to deliver 500 to 600 mL over 1 second, watching for chest rise.
   • If the tube has been accidentally decannulated and cannot be safely re-inserted, or if air is leaking from a loose tube, remove the tube and seal a pediatric round mask directly over the stoma to provide BVM ventilations.
   • For a patient with a tracheostomy experiencing air leak around the stoma, a second rescuer must pinch the patient's nose and hold the mouth shut to prevent air escaping through the upper airway.
   • For a laryngectomy patient, ventilate solely through the stoma; never attempt to ventilate or seal the nose and mouth.

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Clinical Scenario: Refractory Hypoxemia Post-Cardiac Arrest with SGA DOPE Troubleshooting

Prehospital Encounter: Advanced Airway Complication

Paramedics achieve Return of Spontaneous Circulation (ROSC) in a 64-year-old male following 12 minutes of CPR for ventricular fibrillation. During resuscitation, the crew placed a size 4 i-gel supraglottic airway without difficulty, achieving crisp rectangular capnography waveforms (PetCO2 42 mmHg) and bilateral chest rise.

Acute Deterioration:
Three minutes after ROSC, the transport monitor's high-pressure ventilator alarm sounds. The paramedic squeezing the BVM notes immediate, rock-hard resistance. The continuous capnography waveform abruptly disappears, flatlining at 0 mmHg. The patient's SpO2 drops rapidly from 94% to 74%, and the pulse climbs to 138 bpm.

Executing the DOPE Protocol:
The lead paramedic immediately initiates the DOPE protocol:

• D (Dislodgement): The paramedic inspects the depth marker on the i-gel bite block. The marker, which was previously seated at the incisors, has slipped outward by 4 cm due to patient movement during stretcher loading. The cuff bowl has migrated up into the oral pharynx.
• Correction: The paramedic releases the securing strap, opens the mouth, gently glides the i-gel back along the palate until firm resistance is felt, and re-seats the bite block against the teeth.
• Verification: Manual ventilation is delivered: the high resistance vanishes instantly. Auscultation confirms bilateral vesicular breath sounds in the axillae and silence in the epigastrium. The capnography monitor displays an immediate rectangular waveform with a PetCO2 of 38 mmHg. SpO2 rebounds to 97% within 45 seconds. The crew re-secures the device firmly, passing a 12 Fr gastric tube to vent 150 mL of air from the stomach, and completes an uncomplicated transport to the cardiac catheterization laboratory.

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Exam Pitfalls & High-Yield Pearls

• SGA Sizing Basis: Exam questions often test how SGAs are sized. Remember that the i-gel is strictly weight-based (Size 3: 30-50 kg; Size 4: 50-90 kg; Size 5: >90 kg), whereas King LT devices utilize height/weight categories.
• No Cuff Inflation for i-gel: The i-gel features a non-inflatable medical elastomer cuff. Attempting to inject air into the gastric port or body of an i-gel will ruin the device.
• Waveform Capnography Requirement: Rectangular continuous waveform capnography is the definitive objective standard for airway confirmation. A colorimetric detector (litmus paper) is qualitative and susceptible to false positives/negatives; quantitative waveform is superior.
• DOPE Order: When ventilation fails, walk methodically through D-O-P-E. Do not jump to needle thoracostomy (P) before verifying that the tube is not simply dislodged (D) or kinked (O).
• Neck Breathers: In a total laryngectomy, the trachea is permanently wired to the neck stoma. You cannot ventilate through the mouth or nose. In a tracheostomy, the upper airway remains connected, so mouth/nose occlusion may be required if air escapes during stomal ventilation.